The following presentation of mine (via .pdf document) is an attempt to show that H. verticillata is not synonymous with Hoya acuta (H. parasitica the non homotypic specimens mentioned by Traill).
Ganges Hoya .pdf document (1 MB): .pdf document
I am again trying to resolve all the material relating to the Denmark Herbarium material of Vahl's species collected evidently in 1804. For years I have been troubled by the photocopies of the images on Vahl's sheets labeled Sperlingia opposita 6:114 (1804) and Sperlingia verticillata 6:113 (1804), identified by Ruurd van Donkelaar in March 1996 as Hoya parasitica (Roxb.) Wall ex Trail. The foliage and venation of these two species are different and the venation did not appear to me to be like (H. parasitica) Hoya acuta Haworth.